Carburetor construction having a removable small venturi cluster



Dec. 2 7, 1960 Original Filed Dec.

BALL 2,966,344

T. M. CARBURETOR CONSTRUCTION HAVING A REMOVABLE SMALL VENTURI CLUSTER 4 Sheets-Sheet 1 INVENTOR. 75077r4s )7, Z477 BY i/m M/ F i Dec. 27, 1960 T. M. BALL 2,966,344 CARBURETOR CONSTRUCTION HAVING A REMOVABLE SMALL VENTURI CLUSTER Original Filed Dec. 2, 1955 4 Sheets-Sheet 2 I N V EN TOR. 7/;0 777%5 ff 54/] Dec. 27, 1960 2,966,344

T. M. BALL CARBURETOR CONSTRUCTION HAVING A REMOVABLE SMALL VENTURI CLUSTER Original Filed Dec. 2, 1955 4 Sheets-Sheet 3 C k INVENTOR. 7 I id I 74 7/;0777/6 ,F

H BY

Dec. 27, 1960 2,966,344

4 Sheets-Sheet 4 T. M. BALL CARBURETOR CONSTRUCTION HAVING A REMOVABLE SMALL VENTURI CLUSTER Original Filed Dec. 2, 1955 IN VEN TOR. 7'/?& 777 as M 34/ CARBURETOR CONSTRUCTION HAVING A RE- MOVABLE SMALL VENTURI CLUSTER Thomas M. Ball, Bloomfield Hills, Mich., assiguor t Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Continuation of applications Ser. No. 550,536, Dec. 2,

1955, and Ser. No. 697,506, Nov. 15, 1957. This application June 8, 1959, Ser. No. 818,971

13 Claims. (Cl. 26141) My invention relates generally to liquid fuel carburetors for use with internal combustion engine fuel systems. More particularly, my invention relates to an improved carburetor construction wherein portions of the fuel metering elements thereof may be formed independently of the main carburetor body thereby making it possible to introduce many improvements which have not heretofore been possible with carburetors of conventional construction.

This application forms a continuation of my copending applications Serial No. 550,536, filed December 2, 1955, and Serial No. 697,506, filed November 15, 1957, now abandoned, which are continuations-in-part of my application Serial No. 378,001, filed September 2, 1953, issued August 7, 1956 into Patent No. 2,757,914, which in turn is a continuation of my application Serial No. 299,195, filed July 16, 1952, the latter being now abandoned. It will be appreciated that the principles of my instant invention may be applied to types of carburetors other than the double-barrel variety as represented by the carburetor disclosed in my copending application and in this application.

Liquid fuel carburetors are normally comprised of a main carburetor body of cast construction in which is formed a fuel and air mixing conduit, said conduit communicating with the air intake manifold system of the engine. A throttle valve is disposed within the mixing conduit for regulating the rate of delivery of the combustible fuel and air mixture to the intake manifold.

It has been common practice to form a venturi throat section within the mixing conduit and to form a second smaller venturi on the upstream side of the throat section venturi, said throat section venturi being hereinafter referred to as the large venturi. A main liquid fuel nozzle is situated with its discharge end within the small venturi and is responsive to variations in the static pressure head within the small venturi to discharge a continuous, controlled, liquid fuel charge, usually in emulsified form, into the induction air stream. The main nozzle is supplied with a steady liquid fuel charge by means of a fuel well which communicates with the nozzle through a suitable nozzle passage.

The small venturi is situated centrally within the fuel mixing conduit with the discharge end thereof located within the throat section of the large venturi. Such an arrangement gives a relatively high static pressure drop for a given air flow rate through the fuel mixing conduit without causing any undue restriction to the free passage of air through the carburetor to the manifold system. With such an arrangement it is possible to obtain a static pressure drop within the small venturi which is approximately twenty times the total static pressure drop through the carburetor for a given air flow, and the vacuum signal produced by the small venturi is adequate to assure efiicient carburetion at very low engine speeds as Well as at higher speeds.

Although the need for such an arrangement of elements has long been recognized, the carburetors heretofore introduced are usually of an integral construction United States Patent G wherein the small venturi structure is cast integrally with the main carburetor body, both the large and small venturi being formed during the same casting operation. Further, the formation of the above mentioned fuel well has heretofore caused a considerable degree of difficulty because of the complex machining operations required. In those cases where the fuel well is formed during the casting of the main body portion, the dimensions and location of the well are often chosen to facilitate the casting operation although such dimensions or location might not be the most strategic or advantageous from a performance standpoint. Further, the complex contours and thin walls of the carburetor body portion located in the vicinity of and defining the small and the large venturis was such that the casting operation was extremely difiicult and the resulting cast structure was inefficient aerodynamically. Also, the reduced thickness of the structure in the vicinity of the small venturi required the use of a relatively expensive and heavy zinc alloy metal for the entire cast body.

According to a principal feature of my instant invention I have developed a cast carburetor construction in which the small venturi structure is formed independently of the large venturi and of the cast carburetor body portion thereby greatly facilitating manufacture and assembly. Further, this multiple part construction also provides certain manufacturing economies, improves the fluid flow characteristics thereby improving the overall carburetor performance, and results in increased dimensional accuracy of certain critical components as well as other improvements hereinafter described. Further, I have incorporated certain of the fuel metering elements of the carburetor into the small venturi structure to form a unitary cluster of compact and eflicient configuration which may be readily removed for servicing.

The improved carburetor construction of the type briefly mentioned being a principal object of my invention, it is a further object of my invention to provide a carburetor having a small venturi and a large venturi as above described wherein the small venturi comprises an independent unit formed separately from the main carburetor body and wherein the fuel metering well is partly defined by the small venturi structure, the remaining portion of the fuel metering well being formed within the carburetor body.

Another object of my invention is to provide a carburetor as set forth in the preceding objects wherein a small venturi structure is formed of multiple pieces to facilitate a die casting operation.

Another object of my invention is to provide a cast carburetor having a separate small venturi, as above described, wherein the small venturi structure defines in part the porting for distributing the liquid fuel to the main fuel nozzle within the small venturi and to the upstream side of the large venturi.

It is a further object of my invention to provide a cast carburetor having an independently formed small venturi structure wherein the latter is formed with aerodynamically correct dimensions.

It is a further object of my invention to provide a carburetor as set forth in the preceding objects wherein the small venturi structure is secured to the main carburetor cast body by means of hollow elongated screws which are capable of functioning as idle air bleed and idle restriction passages, one end of said hollow screws communicating with the air inlet side of the fuel mixing conduit.

It is a further object of my invention to provide a carburetor having an independent small venturi element capable of conveniently accommodating a main fuel nozzle and wherein a portion of the small venturi structure functions to support the main vent and the idle tube for the fuel metering well.

A further object of my invention is to provide a carburetor having an independently formed small venturi wherein the venturi structure is formed of a material different than that of the main carburetor body.

It is a further object of my invention to provide a carburetor as set forth in the preceding objects wherein the main carburetor body is comprised of cast aluminum and wherein the venturi structure itself may be formed of Zinc alloy, of plastic, or of any other suitable casting material.

It is a further object of my invention to provide an improved carburetor construction wherein the small venturi structure and the principal fuel metering elements may be conveniently removed from the main carburetor assembly and replaced by a similar subassembly or cluster having different fuel metering characterists thereby permitting an alteration in the engine performance as desired at a relatively minor cost.

It is a further object of my invention to provide a carburetor of the type above mentioned which may be interchangeably used with engines of different size or of different air capacities merely by replacing the independent small venturi cluster and its associated fuel metering elements.

For the purpose of particularly describing my improved carburetor construction, reference will be made to the accompanying drawings wherein: Figure 1 shows an outside elevation view of a dual barrel carburetor capable of being used in an automotive type internal combustion engine;

Figure 2 is a plan view of the carburetor construction of Figure 1;

Figure 3 is a sec't ional view of the carburetor of Figures l and 2 taken along an irregular plane identified in Figure 2 by section line 3-3;

Figure 4 is a sectional view taken along an irregular plane identified in Figure 2 by section line 44;

Figure 5 is a detail plan view of the upper portion of the small venturi structure best seen in Figure 3;

Figure 6 is a detail elevational view of the portion of the small venturi structure illustrated in Figure 5;

Figure 7 is a plan detail view of the lower portion of the small venturi structure shown in Figures 3 and 4; Figure 8 is a detail elevational view of the structure of the portion of the venturi structure shown in Figure 7;

Figure 9 is a cross sectional view of a carburetor having a modified small venturi cluster; and

Figure 10 is a plan view of the carburetor of Figure 9 with a portion of a small venturi cluster removed.

Referring first to Figures 1 and 2, the carburetor construction therein illustrated is comprised of three principal portions identified by numerals 10, 12 and 14. By preference these carburetor body portions are formed of cast aluminum by reason of the relatively good heat transfer qualities, good casting properties and low cost of this metal. The upper cast body portion 10 defines a circular air induction passage 16 about which is formed a shoulder 18 to facilitate the assembly of a conventional air cleaner, not shown, on the upstream side of the passage 16. A choke valve, preferably of the offset type, may be mounted within the induction passage 16 for controlling the opening of the passage 16, said valve being rotatably mounted on a choke valve shaft 20 transversely situated and rotatably mounted in the upper cast body portion ll). A thermostatically controlled choke valve actuating mechanism 22 may be mounted on the side of the upper carburetor body portion 19, as best seen in Figure 2, and the thermostatic element there-of may be operatively connected to the choke valve shaft 2% for rotating the same to a choke closing position when the engine operating temperatures are low to facilitate starting and warmu-p operation of the engine, said choke valve shaft carrying thereon a choke valve element 21 illustrated in Figure 2 in the open position. The upper body portion 10 and the intermediate body portion 12 are formed with mating flanges 24 and 26 to permit the same to be secured together by means of bolts 28.

The intermediate body portion 12 is formed with a pair of venturi throat portions designated in Figure 2 by numerals 30 and 32 which communicate with the upper induction passage 16, said throat portions each defining one of the above-mentioned large venturis which will hereinafter be referred to by these same numbers 3t and 32. The air induction passage within the intermediate body portion 12 is separated from the remaining sections of the body portion 12 by a transverse wall identified in Figure 2 by numeral 34, and a fuel bowl section of the intermediate body portion 12 is situated on the other side of wall 34, said fuel bowl being identified in Figures 1 and 2 by numeral 36. The fuel bowl section 36 is capable of storing a supply of liquid fuel and it communicates with a fuel supply line designated in Figure l by numeral 38, a suitable fitting 4-1 being provided for this purpose. The degree of communication between the interior of the fuel bowl section 36 and the fuel delivery line 38 may be regulated by a float controlled valve in the conventional manner. The top of the fuel bowl section 36 is covered by an extension 40 of the upper body portion 10 thereby completely enclosing the interior of the former. The extension or cover 40 is apertured to slidably receive a piston rod 42 for an accelerator pumping mechanism which will later be described in connection with Figure 4. The upper end of the piston rod 42 is joined to a lost motion linkage comprising the lost motion elements 4 and 46, the latter being joined to a manually operated throttle linkage element 48 by means of a connecting link 50. The throttle linkage element 48 may be manually operated in the conventional manner and is joined to a throttle valve rod 52 rotatably mounted in the lower carburetor portion 14.

The body portion 14 is secured to the under side of the intermediate body portion 12 by suitable bolts. By preference at least two such bolts 28 may be of the elongated type capable of extending from the upper body portion flange 24 to the lower body portion 14, said bolts being threadably received in a lower flange 56 situated in mating relationship with respect to a flange 54 formed on the intermediate body portion 12.

If desired, the lower body portion 14 may be suitably cored to permit the circulation of liquid coolant therethrough to prevent icing conditions from developing, the cored passages communicating with an integrally formed hose connection shown in Figures 1 and 2 by numeral 58. Another fitting 69 is formed on the opposite side of the lower body portion 14, as indicated in Figure 2, to provide a continuous circuit for the circulation of liquid coolant through the cored passages. The lower body portion 14 may also be formed with mounting flanges 62 to facilitate the mounting of the carburetor 0n the engine intake manifold.

Referring next to Figure 3, the interior construction of the intermediate body portion 12 is shown in more particular detail. It will be apparent from an inspection of Figure 3 that the large venturi section 30 is situated in the lower end of the air induction passage on the upstream side of a throttle valve 64-, the latter being carried by the above-mentioned throttle valve shaft 52 within an intake manifold conduit 66 defined by the body portion 14. The conduit 66 communicates with and forms an extension of one of the conduits of the engine manifold system. It will also be apparent from Figure 3 that the fuel bowl section 36, the transverse wall 34 and the large venturi portion 312 are formed as part of the integrally cast intermediate body portion 12 and that the body portion 12 is relatively free of complex curvatures and thin walled sections. An embossment 68 extends from the transverse wall 34 to the right, as viewed in Figure 3, and issituated substantially along the line er symmetry of the large venturis 30 and 32, said emboss? ment '68 comprising a portion of the integral cast assembly.

The above-mentioned metering fuel well may be defined in part by a cored opening 70 formed in a vertical direction in the embossment 68, the upper surface of the embossment 68 lying in a substantially horizontal plane, as indicated at 72. The small venturi associated with the large venturi 30 is illustrated in Figure 3 by numeral 74 and by preference it is formed of a cast construction having relatively thin walls defining a venturi throat 76. The small venturi 74 includes an integral extension 78 which in turn is joined to an intermediate venturi section 80 bridging the extension 78 with a corresponding extension for the small venturi associated with the other large venturi 32, said extensions and said intermediate venturi section 80 together with the venturi proper 74 forming a separate, unitary casting.

The cored opening 70 communicates with an opening 82 formed in the intermediate venturi section 80, said opening 82 thereby forming a portion of the metering fuel well.

The small venturi assembly illustrated in Figure 3 is further comprised of an upper cap member 84 which may be formed integrally with the extension 78, or may comprise a separate casting as shown. Member 84 is situated on the upper surface of extension 78 and the intermediate section 80 and comprises therewith a mounting portion of the venturi assembly whereby the latter is mounted on the upper supporting surface 72 of the well or embossment 68. The cap member 84 has a recess 86 forming an upper extension of the aforementioned fuel metering well defined in part by the openings 70 and 82. The cap member 84 is also formed with an extension 88 which covers the upper surface of the extension 78. A downwardly extending nozzle passage 90 is formed in the extension 78 and is also partly defined by a recess 92 formed in the extension 88 of the cap member 84. A hollow nozzle element 94 may be inserted into the nozzle passage 90 prior to assembly of the cap member 84, said nozzle element 94 being retained in its associated passage by means of a press fit. The terminal end of the nozzle 94 is within the throat section 76 of the venturi 74 and the upper end of the nozzle passage defined in part by the recess 92 communicates with the recess 86 to provide communication between the nozzle 94 and the metering fuel well.

A vent or partitioning tube 96 is secured within a first opening 98 formed in the upper cap member 84 of the small venturi structure and it extends downwardly into the well defined by the openings 70 and 82. The tube 96 is hollow and is formed with a plurality of ports 100 which permit the transfer of air from the interior of the tube to the liquid fuel for emulsifying the same. The hollow interior of tube 96 communicates with the air induction passage 16 through a restricted port 102 which is situated within the moving air stream during operation of the engine.

A second opening 104 is formed in the upper cap member 84 for the purpose of retaining therein the upper end of a hollow idle tube 106. The idle tube 186 communi cates with the bottom of the fuel well through a port 108 and it communicates with a third opening 110 in the upper cap member 84, through a communicating passage 112, said passage being defined in part by a port situated at the upper end of the idle tube 106. The opening 110 is aligned with an opening 114 formed in the section 80 of the small venturi structure and with a threaded opening 116 in the embossment 68. A hollow clamping bolt 118 is received through the openings 110 and 114 and is threaded within the threaded opening 116 for the purpose of clamping the cap member 84 and the other portions of the small venturi structure into fixed engagement with the embossment 68. Fibrous gaskets 120 and 122 may be interposed between the cap member 6 84 and the venturi section and between the venturi section 80 and the upper surface 72 of the embossment 68.

Bolt 118 is formed with a central opening 124 which communicates through a restricted passage 126 with the air induction passage 16 for the purpose of obtaining a combustible fuel and air mixture for engine idling purposes. This air is conducted through the central opening 124 and through a communicating passage 128 to an idle port 130 formed in the wall of the manifold conduit 66 in the lower cast body portion 14. The degree of restriction offered by the port 130 may be varied by a valve element 132 threadably connected to the lower cast body portion 14 to eflfect a manual idle adjustment.

In addition to the advantages arising out of the above described dual function of the clamping bolts 118, the bolts 118 also have a certain degree of stretch due to their elongated length thereby compensating for any gasket shrinkage which might occur. Also, since the need for providing a separate idle air passage is eliminated, the size of the cast structure in the vicinity of the venturi cluster can be made correspondingly smaller.

The interior of fuel bowl section 36 has mounted therein a main metering element 134 threadably received in the floor thereof as indicated at 136. The metering element 134 is situated substantially on the plane of symmetry of the fuel bowl section and it is formed with a main metering orifice 138 which communicates with a fuel supply passage 140 interconnecting the orifice 138 with the bottom of the fuel well. The upper portion of the metering element 134 slidably receives and guides a metering pin 142. This metering pin 142 is carried by a movable piston 144 which is slidably received in a cylinder 146. The interior of the cylinder 146 below the piston 144 communicates with the intake manifold conduits on the downstream side of the throttle valve element 64 through suitable porting not specifically illustrated in the drawings. It will therefore be apparent that the degree of restriction of the main metering orifice 138 will be varied by the metering pin 142 as the piston 144 is adjustably positioned within the cylinder 146 in response to variations in engine manifold vacuum.

Referring next to Figure 4, the accelerator pumping mechanism and the choke valve are shown in more particular detail, said pumping mechanism including a piston member 148 carried by the above-mentioned piston rod 42. A spring 150 is interposed between the piston member 148 and the cover portion 40 of the upper cast housing portion 10 for biasing the piston 148 in a downward direction. Upon movement of the accelerator linkage mechanism toward a closed throttle position, piston rod 42 is moved in an upward direction by means of the linkage arrangement shown at 50, 46 and 44. As the throttle linkage mechanism is moved toward an open throttle position, a spring 150 biases the piston 148 in a downward direction in a surrounding cylinder wall 152 thereby causing fuel to be ejected through a passage 154 and through a nozzle element 156 into the portion of the induction passage defined by body portion 12, said cylinder wall 152 preferably being integrally cast with the fuel bowl section 36. A portion of the float control fuel inlet valve is indicated in Figure 4 by numeral 158 and the liquid fuel within the fuel bowl communicates with the pumping chamber below the piston 148 through a fuel supply passage 160 which is controlled by a suitable check valve 162. The nozzle 156 communicates with the induction air passage 16 through a port 164 to prevent a pull over of liquid fuel into the moving induction air stream at high engine speeds. A vent tube 166 is situated on the upstream side of the choke valve 21 for the purpose of venting the interior of the fuel bowl section 36 through suitable internal passages not specifically illustrated.

Referring more specifically to Figures 5 through 8, the details of the small venturi construction are shown in more particular detail. It will be observed that the ven;

turi structure is symmetrically formed and that one venturi element 74 is provided for each of the two mixture conduits. The extensions 88 of the cap member 84, a top view of which is illustrated in Figure 5, are rounded so as to define a leading edge similar to the nose of a double cambered airfoil. The width of the sections 88 is substantially the same as the width of the upper surface of the extensions 78 of the main venturi section illustrated in Figure 7. The thickness of the extensions 78 becomes progressively smaller so that the aerodynamic characteristics of the venturi assembly will be as favorable as possible, said extensions 78 and the extension 88 of the cap member 84 together defining a supporting arm of airfoil type cross section for the venturis 74.

As best seen in Figure 6, the metering tube 106 and the vent tube 106 and 96 respectively for each of the fuel wells are situated in a cluster and form an integral subassembly capable of being positioned in cooperative relationship with respect to the other parts of the small venturi structure illustrated in Figure 7.

Referring next to Figures 9 and 10, I have illustrated another type of small venturi assembly which comprises a pair of venturi elements 274 disposed above the engine intake manifold conduits and which are joined to an intermediate venturi section 286 by means of extensions 278. The venturi construction of Figures 9 and is substantially similar to the venturi construction previously described with respect to Figures 1 through 8 but it differs therefrom in that it provides an additional passage for the fuel discharged from the accelerator pumping mechanism. The discharge nozzles for the accelerator pumping mechanism are formed within the intermediate venturi section 280 as indicated at 256 and they are capable of discharging liquid fuel into the mixture conduits 12. The nozzle openings communicate with an internal passage 254 formed in the intermediate venturi section 280 which in turn communicates with passages 254 and 254" formed in the embossment 63 and the lower side of the intermediate body portion 12. The passage 254" communicates with the cylinder Wall 152 below the piston 148 of the accelerator pumping mechanism.

The small venturi structure of the embodiment of Figures 9 and 10 also difiers from that of Figures 1 through 8 in that the former provides a vent passage for the nozzle openings shown at 256 as indicated by numerals 264, 265 and 266. The portions of the vent passage desig nated by the numerals 264 and 266 are formed in the intermediate section 23f) of the small venturi assembly and they are bridged by a portion of the vent passage designated by numeral 255, the latter comprising a recess within a cap member 284.

The above-mentioned vent tube 166 is interconnected with the passage portion 266 through an internal passage designated by numerals 166' and 166", the passage portion 166' further communicating with the interior of the fuel bowl section 36 in the conventional manner through other branch passages not shown.

The arrangement of the fuel wells with the vent tube and metering tubes may be ascertained from an inspectlon of Figure 10 and it will be observed that it is similar in construction to the above-described embodiment of Figures 1 through 8. The fuel wells are identified in Figure 10 by numerals 82'. A restricted idle air passage may be formed in the clamping bolts shown in Figure 10 by numeral 118 as in the previous embodiment.

The remaining portions of the carburetor construction of Figures 9 and 10 may be identical to that of the previously described embodiment and need not be described in further detail. For convenience, the reference characters applied to the elements of the previously described assembly have also been applied to the corresponding elements of the assembly of Figures 9 and 10 where similarity exists.

The elements of the small venturi structure may be 8 formed of a cast zinc alloy or other suitable casting material. I contemplate that certain plastics or other nonmetallic material may also be employed for this purpose since the strength requirements of the small venturi structure do not exceed that which may be obtained with a material of this type. However, it is preferable to form the carburetor body portion 10, 12, and 14 of a cast aluminum alloy because of its low cost, its light weight, its good casting properties and because of its high heat conductivity. However, such a material would not be suitable for the small venturi assembly because of the sharp and well defined edges which are required, because of the intricate curvatures and chamfers and because of the thin walls of certain of the components thereof. The carburetor body portions may also be formed of magnesium since it has many of the desirable properties of aluminum.

I prefer to form the elements of the venturi structure by means of a die casting operation. Further, since the venturi assembly may be formed separately of the main carburetor body portions, it is possible to cast the fuel well within the embossment 68 of the intermediate body portion 12 since the depth thereof is substantially reduced. Also, the aerodynamics of both the main body portions and the small venturi assembly may be greatly improved since the thickness of the small venturi extensions in the direction of the air flow can be greatly reduced. The integral die cast construction of many conventional carburetors are characterized by thick extensions which obstruct the passage of air through the carburetor. In addition, the upper part of the fuel well which is defined by the small venturi assembly is insulated from the main body portion 12 and will therefore run cooler during engine operation thereby improving the warm weather performance of the engine and reducing percolation, the latter being a common cause of engine flooding during warm weather.

In addition to the foregoing, the unique venturi construction of my instant invention makes it possible to use the same main carburetor body for various size engines since the small venturi assembly or cluster of one carburetor may be substituted with another depending upon the performance desired. This greatly facilitates servicing and testing operations. This feature is also of considerable importance during manufacture since a large portion of conventional cast carburetor bodies having integral small venturi assemblies are rejected because of flaws or dimensional defects in the small venturi assembly. Such rejections can therefore be avoided if the small venturi assembly is made by a separate die casting operation as above indicated. Also inspection procedure during manufacture could be greatly simplified since the venturi assembly may be inspected separately from the main carburetor body.

Although I have particularly described certain preferred constructions of my instant invention, I contemplate that other variations thereof may be made by persons skilled in this art without departing from the scope of my instant invention as defined by the following claims.

I claim:

1. In a liquid fuel carburetor, a body having at least one fuel mixing conduit defined by one portion of said body, a liquid fuel bowl defined by another portion of said body, a wall separating said fuel bowl and said fuel mixing conduit, a large venturi formed Within said mixing conduit, said body including a support located adjacent said separating wall, an opening formed in said support, said opening defining in part a fuel well, a valve controlled fuel passage interconnecting said fuel weli and said bowl, a small venturi assembly removably secured to said support and including a venturi element positioned Within said mixing conduit with the discharge end thereof situated within said large venturi, said venturi assembly further including a mounting portion and 9 an extension interconnecting said mounting portion and said venturi element for positioning the latter, a recess formed in said mounting portion in communication with said opening and partly defining said fuel well, a vent tube and an idle tube secured within said recess, said tubes being adapted to extend into said opening when said venturi assembly is secured to said support, a nozzle opening interconnecting said venturi element with said fuel well, and an idle air passage formed in part in said mounting portion with one end thereof communicating with the upstream side of said mixing conduit and with the other end thereof communicating with the downstream side of said mixing conduit, said'idle tube communicating with said idle passage, and said vent tube being ported to the upstream side of said mixing conduit.

2. In a liquid fuel carburetor, a body, at least one fuel mixing conduit defined by one portion of said body, a liquid fuel bowl defined by another portion of said body, a wall separating said fuel bowl and said fuel mixing conduit, a large venturi formed in said mixing conduit, said body including a support located adjacent said separating wall, an opening formed in said support and partly defining a fuel well, a metering valve controlled fuel passage interconnecting said fuel well and said fuel bowl, a venturi assembly including a venturi element positioned within said mixing conduit, said venturi assembly including a mounting portion having an extension thereon joining said venturi element to said mounting portion, a recess formed in said mounting portion communicating with said opening and partly defining said fuel well, an idle tube secured to said mounting portion within said recess, said tube being adapted to be received within said opening, a nozzle opening interconnecting said venturi element with the interior of said fuel well, an idle air passage partly formed in said mounting portion with one end thereof communicating with the upstream side of said mixing conduit, a port formed in said mounting portion interconnecting said idle air passage and said idle tube, and a clamping means for securing said mounting portion to said support including a hollow clamping bolt extending through said mounting portion, said clamping bolt defining a portion of said idle air passage.

3. In a liquid fuel carburetor, a body, at least one air and fuel mixing conduit defined by one portion of said body, a liquid fuel bowl defined by another portion of said body, a wall separating said fuel bowl and said mixing conduit, said body including a support located adjacent said separating wall, an opening formed in said support and at least partly defining a fuel well, a fuel passage interconnecting said fuel well and said fuel bowl, a venturi assembly including a venturi element positioned within said mixing conduit, said venturi assembly including a mounting portion having an extension thereon joining said venturi element to said mounting portion, an idle tube and a partitioning tube extending from said mounting portion into said well, said partitioning tube being ported at locations along its length into said well, one of two openings comprising the opening defined by said fuel well and the opening defined by said partitioning tube being ported to an upstream portion of said mixing conduit, a nozzle opening interconnecting said venturi element with the other of said two openings, an idle passage having one end vented to air pressure equal to the pressure at an upstream portion of said mixing conduit and the other end discharging into a downstream portion of said mixing conduit, a port interconnecting said idle passage and said idle tube, and a means for securing said mounting portion to said support.

4. The combination according to claim 3 wherein said venturi assembly includes an insulating gasket interposed between said mounting portion and said support for insulating said venturi assembly from said body.

5. In a liquid fuel carburetor, a body having at least one fuel mixing conduit defined by one portion of said body, a liquid fuel bowl defined by another portion of said body, a wall separating said fuel bowl and said fuel mixing conduit, said body including a support located adjacent said separating wall, an opening formed in said support, said opening defining at least in part a fuel well, a fuel passage interconnecting said fuel well and said bowl, a venturiv assembly removably secured to said tube extending from said mounting portion into said well, one of two openings comprising the opening defined by said fuel well and the opening defined by said partitioning tube being ported to an upstream portion of said mixing conduit, a nozzle opening interconnecting said venturi element with the other of said two openings, and an idle passage formed in part in said mounting portion with one end thereof communicating with the upstream side of said mixing conduit and with the other end thereof communicating with the downstream side of said mixing conduit, said idle tube communicating with said idle passage.

6. In a liquid fuel carburetor, a body, at least one air and fuel mixing conduit defined by one portion of said body, a liquid fuel bowl defined by another portion of said body, a wall separating said fuel bowl and said mixing conduit, a large venturi formed in said mixing conduit, said body including a supoprt located adjacent said separating wall, an opening formed in said support and partly defining a fuel well, a metering valve controlled fuel passage interconnecting said fuel well and said fuel bowl, a venturi assembly including a small venturi element positioned within said mixing conduit, said venturi assembly including a mounting portion having an extensionthereon joining said venturi element to said mounting portion, a recess formed in said mounting portion communicating with said opening and partly defining said fuel well, an idle tube and a partitioning tube having a plurality of vertically spaced ports and being secured to said mounting portion within said recess, said tubes being adapted to be received within said opening, one of two openings comprising the opening defined by said fuel well and the opening defined by said partitioning tube being ported to the upstream side of said mixing conduit, a no-zzle opening interconnecting said venturi element with the other of said two openings, an idle air passage having one end communicating with the upstream side of said mixing conduit and the other end discharging into the downstream side of said mixing conduit, a port formed in said mounting portion interconnecting said idle air pas sage and said idle tube, and means for securing said mounting portion to said support.

7. In a liquid fuel carburetor, a body, at least one air and fuel mixing conduit defined by one portion of said body, a liquid fuel bowl defined by another portion of said body, a wall separating said fuel bowl and said mixing cOnduit, a large venturi formed in said mixing conduit, said body including a support located adjacent said separated wall, an opening formed in said support and partly defining a fuel well, a fuel passage interconnecting said fuel Well and said fuel bowl, a venturi assembly including a small venturi element positioned within said mixing conduit, said venturi assembly including a mounting portion having an extension thereon joining said venturi element to said mounting portion, a recess formed in said mounting portion communicating with said opening and partly defining said fuel well, an idle tube and a partitioning tube having a plurality of vertically spaced ports and being secured to said mounting portion within said recess, said tubes being adapted to be received within said opening, one of two openings comprising the opening defined by said fuel well and the opening definedbysaid partitioning tube being ported to the upstream side of said mixing con 11 duit, a nozzle opening interconnecting said venturi element with the other of said two openings, an idle air passage having one end communicating with the upstream side of said mixing conduit and the other end discharging into the downstream side of said mixing conduit, a port formed in said mounting portion interconnecting said idle air passage and said idle tube, and means for securing said mounting portion to said support.

8. In a liquid fuel carburetor, a body, at least one air and fuel mixing conduit defined by one portion of said body, a liquid fuel bowl defined by another portion of said body, a wall separating said fuel bowl and said mixing conduit, said body including a support located adjacent said separating wall, an opening formed in said support and at least partly defining a fuel well, a fuel passage interconnecting said fuel well and said fuel bowl, a venturi assembly including a venturi element positioned with in said mixing conduit, said venturi assembly including a mounting portion having an extension thereon joining said venturi element to said mounting portion, an idle tube and a partitioning tube extending from said mounting portion into said well, said partitioning tube being ported at locations along its length into said well, one of two openings comprising the opening defined by said fuel well and the opening defined by said partitioning tube being ported to an upstream portion of said mixing conduit, a nozzle opening interconnecting said venturi element with the other of said two openings, an idle passage discharging into a downstream portion of said mixing conduit, a port interconnecting said idle passage and said idle tube, and means for securing said mounting portion to said support.

9. In an internal combustion engine having a fuel and air mixing conduit, a carburetor, a body having a port defining at least a portion of said mixing conduit, a liquid fuel bowl defined by another port of said body, a wall separating said fuel bowl and conduit, a venturi in said mixing conduit, said body including a support adjacent said wall for a nozzle assembly, a fuel well defined at least in part by said support, fuel passage means interconnecting said fuel well and said fuel bowl, a removable nozzle assembly including a mounting portion having an extension thereon joining said nozzle assembly to said mounting portion, an idle tube and a partitioning tube recessed into said mounting portion and secured thereto and extending into said fuel well, said partitioning tube having a plurality of ports spaced longitudinally thereof and opening into said well, one of the elements comprising said fuel well and said partitioning tube being ported to air pressure equal to the pressure at an upstream portion of said mixing conduit, nozzle means interconnecting said venturi with the other of said elements, a hollow clamping bolt extending through said mounting portion and removably securing the same to said support, the upper end of said hollow bolt being ported to air pressure equal to the pressure at an upstream portion of said mixing conduit, said hollow bolt being also ported to a downstream portion of said mixing conduit to comprise an idle passage, said mounting portion and hollow bolt also having registering ports interconnecting said idle tube and idle passage.

10. In a liquid fuel carburetor, a body, at least one fuel mixing conduit defined by one portion of said body, a liquid fuel bowl defined by another portion of said body, a venturi formed within said mixing conduit, said bodyincluding a support for a nozzle assembly, an opening formed in said support, said opening defining in part a fuel well, a fuel passage interconnecting said fuel well and said fuel bowl, a nozzle assembly removably secured to said support and including a mounting portion having an extension, a venturi cap member positioned on said mounting portion, an opening formed in said mounting portionand partly defining said fuel well, a vent tube and an idle tube secured to said cap member and extending through the openingsin said mounting portion and in said support, a portion of said cap member overlying said ex tension with the upstream side thereof being rounded to reduce aerodynamic resistance, a nozzle passage formed in said extension and interconnecting said fuel well and the interior of said venturi, an idle air passage extendingthrough said cap member and said mounting portion, a port formed in said cap member and interconnecting said idle tube and said idle air passage, and means for securing said cap member and said mounting portion to said support.

11. In a liquid fuel carburetor, a body, at least one fuel mixing conduit defined by one portion of said body, a liquid fuel bowl defined by another portion of said body, a wall separating said fuel bowl and said fuel mixing conduit, a large venturi formed within said mixing conduit, said body including a support located adjacent said separating wall, an opening formed in said support, said opening defining in part a fuel well, a fuel passage interconnecting said fuel well and said fuel bowl, a small venturi assembly removably secured to said support and including a venturi element positioned within said mixing conduit with the discharge end thereof situated within said large venturi, said venturi assembly including a mounting portion having an extension joined to said venturi element for positioning the latte-r, a venturi cap member positioned on said mounting portion, an opening formed in said mounting portion and partly defining said fuel Well, a vent tube and an idle tube secured to said cap member and extending through the opening in said mounting member and in said support, a portion of said cap member overlying said extension with the upstream side thereof being rounded to reduce aerodynamic resistance, a nozzle passage formed in said extension and interconnecting said fuel well and the interior of said venturi element, an idle air passage extending through said cap member and said mounting portion, a port formed in said cap member and interconnecting said idle tube and said idle air passage, and means for securing said cap member and said mounting portion to said support.

12. In a liquid fuel carburetor, a body, at least one mixing conduit and a fuel mixing conduit defined by one portion of said body, a liquid fuel bowl defined by another portion of said body, a wall separating said fuel bowl and said fuel mixing conduit, a large venturi formed in said mixing conduit, said body including a support located adjacent said separating wall, an opening formed in said support and partly defining a fuel well, a metering valve controlled fuel passage interconnecting said fuel well and said fuel bowl, a venturi assembly including a venturi element positioned within said mixing conduit, said venturi assembly including a mounting portion having an extension thereon joining said venturi element to said mounting portion, said extension having a double cambered cross section with a thickness which varies from a maximum near the upstream side thereof to a minimum on the downstream side, said upstream side of theextension being rounded to provide a minimum degree of aerodynamic resistance, a recess formed in said mountingportion communicating with said opening and partly defining said fuel well, an idletube secured to, said mounting portion within said recess, said tube being adapted to be received within said opening, a nozzle opening interconnecting said venturi element with the interior of said fuel Well, an idler air passage partly formed in said mounting portion with the one end thereof communicating with the upstream side of said mixing conduit, a port formed in said mounting portion interconnecting said idle air passage and said idle tube, and a clamping means for securing said mounting portion to said support including a hollow clamping bolt extending through said mounting portion, said clamping bolt defining a portion of said idle air passage.

13. In a liquid fuel carburetor, a body, at least one fuel mixing conduit defined by one portion of said body,

13 a liquid fuel bowl defined by another portion of said body, a wall separating said fuel bowl and said fuel mixing conduit, a large venturi formed within said mixing conduit, said body including a support located adjacent said separating wall, an opening formed in said support, said opening defining in part a fuel well, a fuel passage interconnecting said fuel well and said fuel bowl, a small venturi assembly removably secured to said support and including a venturi element positioned within said mixing conduit with the discharge end thereof situated within said large venturi, said venturi assembly including a mounting portion having an extension joined to said venturi element for positioning the latter, a venturi cap member positioned on said mounting portion, an opening formed in said mounting portion and partly defining said fuel well, a vent tube and an idle tube secured to said cap member and extending through the opening in said mounting member and in said support, a portion of said cap member overlying said extension with the upstream side thereof being rounded to reduce aerodynamic resistance, a nozzle passage formed in said extension and interconnecting said fuel well and the interior of said venturi element, an idle air passage extending through said cap member and said mounting portion, a port formed in said cap member and interconnecting said idle tube and said idle air passage, and clamping means for securing said cap member and said mounting portion to said support, said clamping means including a hollow clamping bolt extending through said cap member and said mounting portion and defining a portion of said idle air passage.

References Cited in the file of this patent UNITED STATES PATENTS 1,929,266 Viel Oct. 3, 1933 2,313,258 "Olson Mar. 9, 1943 2,327,592 Chisholm Aug. 24, 1943 2,568,987 Brunner Sept. 25, 1951 2,621,030 Henning Dec. 9, 1952 UNTTED STATES PATENT eTTTcT: QTEEFEQATEN I CEUHQN December 27, 1960 Patent No 2 ,9c6 344 Thomas; M. Ball t error appears in the above numbered pat- It is Hereby certified the ent requiring correction and that the said Letters Patent should read as corrected below line l8 for characteristy read Column 3, characteristics column 1O line 30 for "sup0prt' read we support line ()0 for "separated" read we separating o Signed and sealed this 23rd day of May 1961a (SEAL) fittest:

ERNEST W. SWIDER Attesting' Officer DAVID L. LADD Commissioner of Patents 

